The present invention relates to an apparatus for filling containers, and more particularly, to a compartmentalized clean air system for a filling machine. The compartmentalized clean air system encloses a machine station, preferably, the filling station, and provides unidirectional, substantially vertical air flow in the station of the filling machine. The compartmentalized clean air system further creates a pressurized region around, for example, the filling station that further enhances the sterility of the filling process.
Current packaging machine integrate various components necessary to fill and seal a container into a single machine unit. Such a packaging machine is used to perform a packaging process, which generally stated, includes feeding carton blanks into the machine to form cartons, sealing the bottom of the cartons, filling the cartons with the desired contents, sealing the tops of the cartons, and then off-loading the filled cartons for shipping.
Trends within the field of packaging machines point toward increasingly high capacity machines capable of rapid, continuous filling and sealing of a very large number of identical or similar packaging containers, e.g., containers of the type intended for liquid contents such as milk, juice, and the like. One such machine is disclosed in U.S. Pat. No. 5,488,812, issued Feb. 6, 1996, and entitled "Packaging Machine." The machine disclosed in that patent includes a plurality of processing stations, each station implementing one or more processes to form, fill, and seal the containers. Each of the processing stations is driven by one or more servomotors that drive the various components of each of the processing stations.
Another type of packaging machine is exemplified by the TR/7.TM. and TR/8.TM. packaging machines manufactured and available from Tetra Pak, Inc. Such machines are of a more conventional type in which many of the components are driven from a common drive motor through, for example, indexing gears and cam mechanisms.
Certain filling machines have various stations. For example, a carton forming station may be provided prior to a sterilizing station. Also a filling station and a sealing station are commonly provided. In some of these machines, the carton path may be enclosed or partially enclosed in a narrow tunnel to provide greater control over the cleanliness of the container during filling operations, etc. However, these tunnels enclosing the carton path are not necessarily optimal. First of all, the tunnels are difficult to clean, if cleaning is even possible due to the tight confines of the carton tunnel. As a result, automatic cleaning methods cannot be easily used with such carton tunnels. In addition, the tunnels make it difficult, if not impossible, to maintain a vertical air flow in the filling machine.
A further disadvantage of the tunnel is that it limits visibility of the cartons in the carton path so that if a crash of the cartons occurs, it cannot be readily be detected. Similarly, access is limited due to the restrictive arrangement of the tunnel enclosing the carton path. A related is that it creates a physical obstruction to manipulating the cartons by mechanical means.
There are also problems associated with known machines having sterile air ventilation systems. For example, these machines have difficulty controlling the air quality and maintaining desired air pressures within the machine. Furthermore, certain systems create recirculation paths for the air flow that allow settling regions for debris, liquid accumulation in the machine, and recontamination of the air stream and subsequently the partially packaged product. Another disadvantage is the inability to automatically clean and sterilize the surfaces in direct contact with the air.